Quantitative Classification of Visual Field Defects in Early Glaucoma.

Area of Science:

• Ophthalmology
• Medical Imaging
• Glaucoma Research

Background:

• Qualitative visual field (VF) grading systems for glaucoma are subjective and prone to interobserver disagreement.
• Objective characterization of VF defects is needed for accurate glaucoma diagnosis and management.

Purpose of the Study:

• To quantitatively characterize the types and frequencies of VF defects in a large cohort of subjects with early glaucomatous loss.
• To evaluate the utility of a quantitative method based on the Ocular Hypertension Treatment Study (OHTS) VF classification system.

Main Methods:

• A cross-sectional study involving 1330 eyes of 733 subjects with healthy, suspect, or early glaucoma.
• Translated the OHTS VF classification system into an objective, quantitative method to identify 14 defect patterns.
• Applied the method to VF tests from subjects who underwent two 24-2 Swedish Interactive Thresholding Algorithm-Faster VF tests per eye.

Main Results:

• The most common repeatable VF defect patterns were inferior nasal step (22.6%) and inferior enlarged blind spot (19.1%).
• Initial defects occurred more frequently than repeatable defects.
• Nasal step defects decreased as mean deviation (MD) worsened, with a rise in arcuate defects.
• Unreliable tests showed higher frequencies of bundle and nonbundle defects.

Conclusions:

• Nasal step, enlarged blind spot, and arcuate defects are the most common VF defects in early glaucoma.
• Significant differences exist in defect distribution between initial vs. repeatable and reliable vs. unreliable tests.
• Quantitative criteria enhance the accuracy and consistency of VF defect classification in glaucoma.